For the fourth straight year, the number of homicides in Boston is on track to fall, this time sharply, and violent crime continues to decline, officials said Monday.
By Monday, there were 40 homicides in Boston, 18 fewer than last year. The reasons given varied, from more focused police work and aggressive prosecution of offenders with guns to better medical care for victims.
Despite that encouraging news, the almost-year-end statistics reveal a troubling reality: Although police continue to confiscate guns, the street supply remains steady enough for overall gun violence to continue unabated. The number of 2013 shootings by Dec. 22 is almost exactly what it was last year: 246.
“Unfortunately, the number of guns aren’t down,” said Acting Police Commissioner William Evans. “That’s the biggest issue we have out there. There are way too many guns still out there.”
In 2013, Boston police seized 663 firearms, including 41 rifles, six assault rifles, and 45 shotguns. That is 125 more weapons than last year, said police.
More officers faced gunfire than last year, and three officers were shot while exchanging gunfire with suspects. That does not include a shootout in Watertown in April between police and the Boston Marathon bombing suspects and the fatal shooting of an MIT police officer earlier that night.
“It was a dangerous year for our officers,” Evans said in an interview Monday.
Evans said that many of the seized guns were stolen from people who bought them legally, or the guns came from other states that have laxer gun laws than Massachusetts.
“You can go into other states and go into Walmart and buy them, and unfortunately sometimes that’s what we end up dealing with here in Massachusetts,” he said.
The 40 homicides tallied so far for this year do not include the three people killed in the April 15 Marathon bombings, which are being investigated by the FBI, or the Feb. 25 fatal stabbing of Corey Thompson, whose body was found underneath the Route 93 overpass in the South End, which is part of State Police jurisdiction. Arrests have been made in those killings.
Boston police identified a suspect in 16 of the 40 killings that fell in their jurisdiction, said Suffolk District Attorney Daniel F. Conley. They also solved seven homicides that occurred in 2012 and one from 1964, the murder of Mary Sullivan, who is believed to be the last victim of the Boston Strangler.
The majority of homicides in Boston are committed with firearms, and the suspect, usually concealed by darkness or a hooded shirt, fires from a car or walks up to a group of people and then runs, Conley said.
“These are the most difficult to solve,” he said. “You’re not getting anything left behind by the suspect. ”
Boston police typically solve 38 percent of those shooting cases a year, Conley said. In cases in which the victim was strangled or stabbed, police are able to solve the crime more than 80 percent of the time.
The 40 homicides this year compares to 58 in 2012, 62 in 2011, and 74 in 2010, reflecting the gradual decrease over the four-year period.
Evans said he believes the number of homicides has gone down in part because police have studied intelligence reports closely, looking carefully at which gangs are feuding and targeting anyone who may seek retribution following a shooting.
Conley said another factor in the decline is the sharpened focus by police and prosecutors on people carrying illegal firearms. In the last eight years, such cases have been referred to a so-called gun court, a session in Boston Municipal Court; five assistant district attorneys are assigned to those cases, and win 85 to 88 percent of the time, Conley said.
“When you take those types of individuals off the street, you’re taking shooters off the street,” Conley said.
Nationwide, in communities that have populations over 600,000, police have reported a slight uptick in the number of homicides, according to federal data.
But other large cities are also reporting decreases. In Chicago, the number of homicides is at 412 so far for the year, compared with 497 in 2012. In New York, there have been 329 homicides through Dec. 22, compared with 413 during the same time last year. And in Los Angeles, there were 246 homicides through Dec. 21, compared with 295 in 2012.
Strong medical care is another factor in the falling number of homicides in Boston, police and emergency care officials agree, helping more shooting victims survive their wounds.
In recent years, a heavy focus has been put on paramedics and emergency medical technicians reaching crime scenes quickly, getting the patient out of the area as quickly as possible, and working on the victim on the way to one of the city’s five trauma centers, which are alerted that a critical patient is coming in, said Jim Hooley, chief of the Boston Emergency Medical Services department.
“We’re trying to shave time off on these kinds of patients all the time,” Hooley said. “There is a real correlation between time and survivability.”
Rufus Faulk, executive director of the Boston TenPoint Coalition, a nonprofit focused on violence prevention, said the decrease in homicides could also be the result of young men simply giving up a life of gangs and guns.
He said that two weeks ago, a 23-year-old man he once knew to carry a firearm told him he was so scared of being gunned down that he could not take his son to day care.
“He wants to change his life for himself and his family,” Faulk said. “They realize that the way of life they’re living can only take them so far.”
Still, even as the numbers of homicides falls, some neighborhoods saw little difference in the rate of violence. Some even saw spikes.
In Roxbury, there were 18 homicides by Dec. 22, compared with 11 at the same time last year. Evans said he is not sure why there is such geographic disparity in killings in the city, but suspects that criminals there could have access to more guns.
Though the number of killings in the city fell overall, Evans said it is not something to celebrate. “We’re not happy that we only have 40 homicides,” Evans said. “Because that’s 40 mothers out there who lost loved ones.”
Globe correspondent Jackie Tempera contributed to this report. Maria Cramer can be reached at maria.cramer@